Recently, as higher performance and more price reduction of computers are increasingly realized, “IT” is rapidly progressed in various fields. For example, in the field of education, it is increasingly common that each student is provided with his/her own personal computer for use during lectures and practices. In order to give such lectures appropriately, it is necessary to appropriately set up software for a lot of personal computers for each lecture.
As functions of software are increasingly complicated, significant time and labor are often required to set up software for a number of computers. Accordingly, it is conceivable to distribute a disk image for replacing the contents of a hard disk drive to each computer via a network when the same software is installed according to the same settings. However, the data size of the disk image is generally very large.
FIG. 14 is a conceptual diagram showing that a disk image is distributed via a wired network. A server device 80 communicates with a layer 2 switching hub via the Gigabit Ethernet®, for example. The layer 2 switching hub communicates with each of personal computers 85-1 to 85-30 via the 100 Base-T Ethernet®. In this case, if the data size of the disk image is assumed to be 5 Gbytes, distribution of the disk image is completed in about one hour. Thus, with the progress of recent communication technology, the communication speed of wired connection has been increased, and in most cases, there is caused no problem in the communication speed in distributing a disk image.
FIG. 15 is a conceptual diagram showing that a disk image is distributed via a wireless network. A server device 90 connects to a wireless LAN access point which is in compliance with the IEEE802.11g standard. The wireless LAN access point communicates with each of personal computers 95-1 to 95-30 at a link rate up to 54 Mbps. However, the effective transfer rate is about 20 Mbps. In this case, since the transfer band of 20 Mbps is shared by the thirty computers, the transfer rate of one computer is about 0.7 Mbps. As a result, if the data size of the disk image is assumed to be 5 Gbytes, more than sixteen hours are required for distribution of the disk image.
There have been proposed various techniques relative to the ad hoc mode for wireless LAN. For example, there has been proposed a technique wherein, when one cluster is constituted by multiple communication devices mutually communicating with each other in the ad hoc mode for wireless LAN, a cluster head for managing the cluster is appropriately selected from among these information processing units (see Japanese Published Patent Application 2002-44003). There has also been proposed a technique wherein, in star connection where one parent machine and multiple child machines are connected in the ad hoc mode for wireless LAN, a communication device to be the parent machine is selected based on the remaining amount of a battery for driving each communication device (see Japanese Published Patent Application 2003-32263).
According to the example in FIG. 14, it is possible to distribute a disk image at a high speed. However, it is necessary to perform wiring and install equipment in order to configure a wired network, which is often troublesome. According to the example in FIG. 15, it takes too much time to distribute a disk image. Therefore, even if distribution is started at a closing time, the distribution is not completed by a starting time of the next day. This causes the rate of facility operation to be very low. Further, since the techniques disclosed in the above patent applications aim at keeping the status of wireless communication in the ad hoc mode optimum, no method for distributing data, such as a disk image, at a high speed is mentioned.